MILITARY strategists inside and outside the federal government are grappling with the most fundamental question of most of their careers. As 40 years of cold war melt away, what roles should the United States military be prepared to fill?
The question has become more urgent because troop and weapons cuts are suddenly under discussion at the Pentagon - mainly for budget reasons - that run far ahead of either international negotiations under way now or any strategic planning.
As the nuclear endgame between the US and the Soviets becomes more unlikely, strategists stress that the world is becoming far more unpredictable. Military threats to American interests are likely to come from a far wider range of sources, such as heavily armed third-world nations or instability in Europe - especially involving a reunited Germany. (NATO leaders stress role of alliance in Europe, Page 3).
The military response to the new world scene will almost certainly need to stress flexibility, with greater emphasis than now on light airborne and amphibious forces and the use of reserve troops, according to a consensus among strategic planners.
Strategists are keenly aware that none of them predicted the speed of present events in Europe, and few expect predictability any time soon.
``That's a lesson that will not be lost on anybody in this business,'' says Michael Rich, vice president for national security research at Rand Corporation.
The Soviets remain the focus of US military strategy for the foreseeable future.
The classic threat of an attack by Warsaw Pact forces across the Fulda Gap into West Germany is disappearing, as Defense Secretary Richard Cheney has noted in recent weeks. The Soviet willingness to allow greater autonomy in even Eastern Europe is no longer in question, and the support of Soviet allies for an attack on the West has become dubious at best.
The risk in Europe is not World War III but World War IV, jokes Loren Thompson of Georgetown University, because the Soviets would have to fight World War III just to reach their own European borders.
But the worst-case military scenario remains a political reversal for Soviet President Gorbachev that puts the country back in hard-line Stalinist hands.
``It would be irresponsible not to allow for that possibility,'' says Al Bernstein, chairman of the strategy department of the Naval War College in Newport, R.I. This is one reason the US needs to maintain a ``fundamental, though diminished'' presence in Europe, he adds.
Although Soviet military spending appears to be dropping, weapons production in many categories is still higher than when Mr. Gorbachev took office in 1985.
Outside of Europe, no significant Soviet retrenchment has appeared.
The Soviets have not yet cut back on military aid to third-world governments, many of them hostile to the US and its interests, Dr. Bernstein says. They are currently selling MIG-29 fighter jets to Libya and North Korea and expanding their presence in Syria.
The US particularly seeks Soviet pressure on Cuba to stop the flow of Soviet arms to Nicaragua and insurgent guerrillas in El Salvador. But so far, says Bernstein, Soviet intentions are not clear.
The most sinister view of the Soviet motive in warming the cold war, a motive that Bernstein calls ``conceivable,'' is that they want to skip one generation of weapons deployment while their economy and technology catch up. The danger here would be that the US slacks off from research and development as insurance against a full-scale Soviet return to the arms race 10 or 15 years from now, Bernstein says.
But the US is increasingly losing the luxury of building strategy around a single enemy. Third-world nations are rapidly acquiring more-threatening weapons as ballistic and cruise-missile technology spreads on the open market.
``The Brazils of the world will never be as dangerous to us as the Soviets,'' says Dr. Thompson, explaining that although such countries may have the nuclear and missile technology, they don't have the ideological or political motivation.
Nevertheless, notes Mr. Rich, ``there are many more plausible threats now.''
Bernstein suggests that a continuing US military presence in regions such as Southeast Asia will be necessary to deter military adventurism by local nations.
Europe has become the scene of greatest uncertainty. As the superpowers prepare to lighten their presence, historic nationalisms and instabilities are already resurfacing, says Jeffrey Simon, senior fellow at the Institute for National Strategic Studies at National Defense University.
At the heart of these potential instabilities is a reunited Germany, a nation responsible for three wars in the past century. The Poles have already tried to get a West German commitment to Germany's present borders and have yet to receive it, Dr. Simon says. ``The Poles very clearly see a security threat from Germany.''
Even if Germany signs a treaty outlining its present borders and sharply limiting its military forces, a new government could call such an agreement into question, observes Richard Betts, senior fellow of the Brookings Institution.
The disappearance of the ``old, predictable order'' in Europe is exciting, Dr. Betts says, but replacing it is ``not necessarily going to be a stable, happy order.''
He is particularly concerned that present euphoria in Eastern Europe over political change will lead to disillusionment without economic improvement soon.